A sputtering technique has conventionally been attempted in which two sputtering cathodes having a target attached thereto are adjacently arranged and a coating comprising the target material is formed on a substrate moving in one direction in front of the targets. In this case, a method has been employed that power sources for applying a negative voltage to the two cathodes are provided with respect to the respective sputtering cathode, and a negative voltage is applied to each cathode through electrically separate lines.
This technique has recently developed into a DMS method in which an inversion voltage is alternately applied to the two sputtering cathodes adjacently arranged and while destaticizing the targets, a coating is formed on the substrate moving in one direction in front of the targets. The DMS method is used as a method suitable to high-rate sputtering.
In order to cover the entire surface of a bulky substrate or both sides of a flat plate-like substrate simultaneously with a coating, the sputtering apparatus must be provided with a driving part so as to coat the substrate while rotating the substrate. On the other hand, electron beam deposition or arc plasma ion plating which achieves a high coating rate and can coat a wide area has problems such that the substrate material to be coated is limited and the composition of the coating is deviated from that of the evaporation material because a component or an element, having different vapor pressure has a different rate of evaporation. It has therefore been demanded to develop a sputtering technique and an apparatus therefor that can form a coating on the entire surface of a substrate by a sputtering method which is relatively free from those problems.